The present invention relates generally to cooling systems for internal combustion engines. More particularly, the present invention relates to cooling system closures having a pressure-relief valve configured to regulate the flow of coolant and vapor from the cooling system and a vacuum-relief valve configured to regulate the return of coolant and vapor to the cooling system.
Internal combustion engines which are liquid cooled incorporate cooling systems having radiators coupled to the engine to dissipate heat generated by the engine. As radiator fluid (i.e., coolant) passes through the radiator, heat is given off to the environment and now relatively cooler fluid is returned to the engine.
After the engine is started, the operating temperature of the engine increases, causing an increase in the pressure in the cooling system. The cooling system closure includes a pressure-relief valve which is normally closed to prevent the escape of radiator fluid when normal pressures are generated within the cooling system. However, when the pressure in the cooling system acting on an area defined by the valve exceeds the closure force applied to the valve by the pressure-relief spring, the valve is "pushed open" by such pressure and radiator fluid is discharged from the radiator past the pressure-relief valve into an overflow tank.
The overflow fluid or coolant is returned to the radiator upon the development of vacuum or subatmospheric pressure within the cooling system after the engine is cooled. The cooling system closure also includes a vacuum-relief valve which is normally open. Typically, the vacuum-relief valve is moved to a closed position by a "surge" of pressure and steam during a relatively quick warmup of the coolant. However, on occasion, the vacuum-relief valve may not be moved to the closed position because the coolant warms up more gradually and no surge develops.
According to the present invention, a cooling system closure includes a closure apparatus and a relief valve. The closure apparatus is adapted to mount on a cooling system and formed to include a flow passage arranged to receive fluid discharged from the cooling system. The relief valve is positioned to move between an opened position permitting fluid to flow through the flow passage and a closed position blocking the flow of fluid through the flow passage. The relief valve includes a temperature-activated element moving to a first position when heated to a first predetermined temperature to urge the relief valve to the closed position and a second position when cooled below a second predetermined temperature to permit the relief valve to move to the opened position.
According to a preferred embodiment of the present invention, the relief valve further includes a valve member and the temperature-activated element is made of a spring material to yieldably urge the valve member to block the flow of fluid through the flow passage when the temperature-activated element is above the first predetermined temperature. According to another preferred embodiment of the present invention, the relief valve further includes a valve member and a spring. When the temperature-activated element is heated above the first predetermined temperature, it cooperates with the spring to urge the valve member to block the flow of fluid through the flow passage. According to yet another preferred embodiment of the present invention, the temperature-activated element is positioned to block the flow of fluid through the flow passage when heated above the first predetermined temperature and to permit the flow of fluid through the flow passage when cooled below a second predetermined temperature.
Additional features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.